Automatic test equipment or ATE is used to test semiconductor or other type devices at various stages of manufacture. Typically, an ATE tester supplies power and test signals, from instrument cards located in a test head, to a device interface board or DIB for routing to selected pins of a device under test or DUT.
As devices continue to operate at ever increasing speeds, and include ever increasing numbers of transistors, providing a stable source of power during dynamic modes of operation becomes problematic. The ATE power supply often responds to dynamic current changes of, for example, 300 amperes, within a few picoseconds. At these levels of current switching performance, inductance and minute resistances pose significant problems, tending to inhibit changes in current, thereby affecting the device-under-test. Typically, during dynamic modes of power supply operation, responsive high current waveforms are supplied by the instrument card to the DIB via a bus bar, or a heavy gauge wire, such as for example a 0.4 AWG cable.
Large diameter cables and bus bars are bulky and not easily maneuvered. This can be undesirable in certain ATE applications. In certain applications, for example, it may influence the positioning of the connector when mating with the DIB, or it can otherwise hinder operations nearby. Further, in precision testing applications, a corresponding return line is also provided between the instrument card and the DIB. Thus, a pair of cables is used, increasing such effects. In a paired force/return cable arrangement, mutual inductance is a concern. Since inductance sums along the length of the cable, this can limit high frequency response. Also, reliable, low inductance connection is not easily provided at low cost.
Conventional laminated foil straps are not easily manufactured to provide reliable interconnection at low cost, and do not provide high current interfacing with extremely low inductance. Such is often desired by ATE testers to provide precision testing of DUT's capable of operating at very high frequency.